Slider -
Mechanism that allows a tandem axle suspension to be moved back and forth at the rear of a semitrailer, for the purpose of adjusting the distribution of weight between the axles and fifth wheel.
Reference: Truck Writers of North America (TWNA)

Sliding Tandem -
Mechanism that allows a tandem axle suspension to be moved back and forth at the rear of a semitrailer, for the purpose of adjusting the distribution of weight between the axles and fifth wheel.
Reference: Truck Writers of North America (TWNA)